The present invention relates generally to rotary heat regenerative heat exchangers and, more specifically, to improved means for supporting and positioning modular heat exchange baskets.
A rotary regenerative heat exchanger is employed to transfer heat from one hot gas stream, such as a flue gas stream, to another cold gas stream, such as combustion air. The rotor contains a mass of heat absorbent material which is first positioned in a passageway for the hot gas stream where heat is absorbed by the heat absorbent material. As the rotor turns, the heated absorbent material enters the passageway for the cold gas stream where the heat is transferred from the absorbent material to the cold gas stream.
In a typical rotary heat exchanger, such as a rotary regenerative air preheater, the cylindrical rotor is disposed on a vertical central rotor post and divided into a plurality of sector-shaped compartments by a plurality of radial partitions or diaphragms extending from the rotor post to the outer peripheral shell of the rotor. These sector-shaped compartments are loaded with modular heat exchange baskets which contain the mass of heat absorbent material commonly comprised of stacked plate-like elements.
The rotor is surrounded by a housing and the ends of the rotor are partially covered by sector plates located between the gas inlet and outlet ducts which divides the housing into hot gas and cold gas sides. In order to improve the efficiency of operation, it is conventional to provide seals, which are referred to as radial seal, on the ends of the rotor such that the seals will come into proximity with the sector plates and minimize the flow of gases between the hot and cold sides at the ends of the rotor. These seals are normally attached to the edges of the diaphragms.
The conventional modular heat exchange basket comprises an open frame and does not have solid side walls. These baskets are loaded axially into the rotor from the top end (duct end) and stay plates are located between and support radially adjacent baskets. To ensure that the baskets can be freely inserted, it is necessary to have the baskets undersized as compared to the compartments formed by the diaphragms and stay plates so that there is a clearance. Therefore, in order to provide the necessary heat exchange surface, it is necessary to have excess frontal area and consequently a larger rotor. Also, gaps exist around each basket permitting the bypass of the air and flue gas thus reducing the thermal efficiency.